Fastener-driving apparatus

ABSTRACT

A pneumatically actuated fastener-driving apparatus is provided which utilizes an air pressure system for effecting return of the drive piston to its firing position. An exterior portion of the drive blade is contoured so as to facilitate complete depressurization of the air return chamber prior to initiating the drive stroke of the drive piston. The head of the drive piston carries an adjustable seal which enables a small amount of pressured air to bleed past the piston head during the drive stroke and thereby facilitate pressure buildup in air return chambers so as to effect more rapid return of the drive piston to its firing position.

United States Patent I72] Inventors James K. Geode, Jr.

Cory; James A. Whlteside, Rolling Meadows, both of Ill. [2i] Appl. No. 15,640 [22] Filed Mtlr. 2, I970 [45] Patented Nov. 23, 1971 [73 Assignee Spotnlils, Inc.

Rolling Meadows, lll.

[54] FASTENER-DRIVING APPARATUS llClaims, 9 Drawing Figs.

Primary Examiner-Granville Y. Custer. Jr. Attorney-Pendleton, Neuman, Williams & Anderson ABSTRACT: A pneumatically actuated fastener-driving apparatus is provided which utilizes an air pressure system for effecting return of the drive piston to its firing position. An exterior portion of the drive blade is contoured so as to facilitate complete depressurization of the air return chamber prior to initiating the drive stroke of the drive piston. The head of the drive piston carries an adjustable seal which enables a small amount of pressured air to bleed past the piston head during the drive stroke and thereby facilitate pressure buildup in air return chambers so as to effect more rapid return of the drive iston'to its firi nsposition.

PATENTEDuuv 23 I971 SHEET 1 [1F 3 PATENTEDNBV 23 I911 3.622.062

SHEET 3 OF 3 FAS'lENER -DRIVING APPARATUS BACKGROUND OF THE INVENTION Various pneumatically actuated fastener-driving apparatus or tools have heretofore been proposed; however, because of certain design characteristics they are beset with one or more of the following shortcomings: (a) return of the drive piston is by spring action which presents maintenance problems because of rapid fatigue occurring in the spring; (b) the driving force of the drive piston is diminished during rapid firing of the apparatus due to stair stepping which is caused by pressure accumulating under the piston head in opposition to the drive force pressure; (c) air return pressure buildup for the drive piston is relatively slow thereby reducing the operating speed of the apparatus; and (d) the apparatus embodies complex valving means to control operation of the drive piston,

thereby increasing the initial cost of the apparatus and complicating the maintenance and servicing of the apparatus.

' SUMMARY OF THE INVENTION Thus, it is an object of this invention to provide a pneumatically actuated fastener-driving apparatus which avoids the aforenoted shortcomings associated with the prior art.

It is a further object of this invention to provide a pneumatically actuated fastener-driving apparatus wherein movement of the valve for effecting the drive stroke of the drive piston automatically controls pressure buildup in the air return chamber for said piston.

It is a further object of this invention to provide a pneumatically actuated fastener-driving apparatus which utilizes an air actuated fastener feed mechanism having an air return system therefor.

It is a still further object of this invention to provide a fastener-driving apparatus which is of simple, sturdy construction, is easy to manipulate, and requires a minimum amount of maintenance.

Further and additional objects will appear from the description, accompanying drawings, and appended claims.

In accordance with one embodiment of the invention a pneumatically actuated fastener-driving apparatus is provided which includes a housing having formed therein a reservoir for pneumatic fluid. Disposed within the housing is an elongated cylinder having one end thereof exposed at predetermined intervals to the pneumatic fluid reservoir. Mounted for reciprocatory movement within the cylinder is a drive piston. The piston includes a head member which is adapted to move between first and second positions during operation of the apparatus. Extending transversely from one surface of the head member is an elongated driver blade. The driver blade extends through an opening formed at a second end of the cylinder. The head member, when in the first position, is disposed adjacent the cylinder one end, and, when in the second position, is disposed adjacent the cylinder second end. The distal end of the driver blade is contoured so that when the head member is in the first position, the periphery of the driver blade is spaced from the perimeter of the opening formed in the cylinder second end. The head member of the drive piston carries an adjustable seal which delimits the periphery thereof and is in sealing contact with the cylinder surface only when the head member is moving from the second to the first positions. Disposed within the housing and adjacent the cylinder one end is a pneumatically responsive first valve member which is mounted for movement between open and closed positions. The valve member, when in an open position, exposes a second surface of the head member to the pneumatic fluid reservoir thereby causing the driver piston to move through its driving stroke. Mounted on the housing is a manually actuated second valve member which is operatively connected to the first valve member and controls the positioning of the latter.

DESCRIPTION For a more complete understanding of the invention reference should be made to the drawings wherein:

FIG. 1 is a fragmentary vertical sectional view of one form of the improved apparatus and showing the drive piston in its fully up position ready for firing.

FIG. 2 is similar to FIG. 1, but showing the piston at the end of its drive stroke.

FIG. 3 is similar to FIGS. 1 and 2, but showing the piston during its return to the fully up position of FIG. 1.

FIG. 4 is an enlarged, fragmentary sectional view taken along line 4-4 of FIG. 3.

FIGS. 5 and 6 are enlarged fragmentary vertical sectional views of one form of the drive piston head member shown, respectively, while moving through the drive stroke, and while moving through the return stroke.

FIGS. 7 and 8 are similar to FIGS. 5 and 6, but showing a modified fonn of drive piston head member.

FIG. 9 is similar to FIGS. 6 and 8, but showing a third form of drive piston head member.

Referring now to the drawings, one form of the improved apparatus 10 is shown in FIGS. 1-3. The illustrated apparatus is in the form of a hand operated tool commonly used by carpenters and the like at building construction jobs. Apparatus 10 is pneumatically actuated and includes a housing 11 provided with a laterally extending hollow handle portion 12 which serves as a reservoir for pneumatic fluid. Portion I2 is provided with a suitable connector, not shown, for receiving one end of a flexible air hose.

Disposed within the housing 11 is an elongated cylinder 13 the upper end of which is closed by a poppet valve 14, when the apparatus is at rest or during other predetermined intervals to be hereafter discussed. Poppet valve 14 is of an annular disclike configuration, the diameter of which exceeds that of cylinder 13, so that a peripheral portion 14a of the valve projects transversely beyond the upper end of the cylinder.

Valve 14 is disposed within a cavity 15 formed in a removable cover 16 for the housing and is responsive to predetermined pneumatic pressures and moves in an endwise direction relative to the cylinder upper end between a closed sealing position, seen in FIGS. 1 and 3 and an open position, seen in FIG. 2. Valve 14 carries on its annular periphery suitable sealing means 17 which sealingly engage the walls of the cavity 15 during movement of the valve.

Disposed within cavity 15 and encompassing an upwardly extending, centrally positioned collar 18 carried by valve I4 is a coil spring 20 which serves .to bias the valve 14 in its closed position with respect to the upper end of cylinder 13. The valve collar 18 is provided with an axial bore 180, the upper end of which communicates at predetermined intervals with an exhaust port 21 formed in cover 16. The lower end of bore communicates also at predetermined intervals with the upper portion of the cylinder interior I.

When the valve 14 is in its open position (see FIG. 2), the upper end of collar 18 interrupts the communication between the collar bore 18a and exhaust port 21 thereby preventing any pneumatic fluid from escaping through port 21. During other times when the valve 14 is not in its fully opened position, the pneumatic fluid disposed within the upper portion l of the cylinder 14 is exhausted to the atmosphere through bore 180 and port 21.

The upper end of the bias spring 20 is maintained in proper position by a depending sleeve 22 which projects into cavity I5. Spring 20 encompasses the exterior of the sleeve, while the latter, in turn, encompasses the collar 18 carried by valve 14. Collar 18 carries an 0 ring type seal 18b which engages the interior surface of sleeve 22.

Disposed within cylinder 13 and mounted for reciprocatory movement is a drive piston 23 which comprises an annular head member 24 and an axially extending driver blade 25 depending from the underside of the head member. The blade 25 has the lower end portion thereof projecting through an opening 26 formed in a bumper piece 27, the latter being mounted at the lower end of the cylinder 13. The bumper piece 27 is formed of resilient material and is engaged by the underside of the head member 24 when the latter has reached the end of the drive stroke, see FIG. 2. The disposition of the bumper piece 27 relative to the lower end of the cylinder 13 may be such as disclosed in pending application Ser. No. 879,316 filed Nov. 24, 1969 so as to produce a fail-safe effect whereby the drive piston will automatically become inoperative once the bumper piece has been subjected to a predetermined amount of wear.

When the drive piston 23 is disposed in its fully up or firing position, see FIG. 1, the distal end 25a of the driver blade 25 is disposed within the opening 26 formed in the bumper piece 27. It will be noted in FIG. I that the blade distal end 25a is contoured or reduced in size so that an annular space S is fonned between the portion of the bumper piece defining the opening and the blade end which functions as an exhaust passage for the pneumatic fluid entrapped within the lower portion 1] of the cylinder interior disposed beneath the head member 24 during rapid return of the drive piston to its firing position. The exhaust passage facilitates rapid depressurizing of the cylinder interior portion II and prevents a condition, known as "stair-stepping" from developing. This condition is one when depressurizing is incomplete and there is a gradual buildup of pneumatic fluid beneath the piston head member 24 until the effectiveness of the pneumatic driving force is seriously diminished.

Mounted on the handle portion 12 of the housing 11 is a trigger actuated valve 28 which controls the application of the pneumatic force so as to effect firing of the drive piston 23. Valve 28 includes a sleeve 30 which is snug-fit into a bore 31 formed in the underside of handle portion 12. Communicating with the bore 31 is a first port 32 formed in the housing 11. Port 32 leads to a pair of second ports 33 and 34, the latter being formed in the housing and extending in opposite directions with respect to one another. Port 33 is directed upwardly and has its upper end communicating with the cavity formed in the cover 16. The other port 34 extends downwardly and has the lower end terminating at a fastenerfeed mechanism 35 which will be described more fully hereinafter.

Carried by the exterior of valve sleeve 30 and disposed above and below the port 21 are 0" ring seals 36. The portion of the sleeve 30 disposed intermediate the seals 36 is provided with a transversely extending opening 30a which is in registration with port 32.

Mounted for reciprocatory movement within sleeve 30 is a plunger 37 which carries adjacent its upper end an 0" ring seal 38 which is in sealing engagement with the interior surface of sleeve 30. The lower portion 370 of the plunger may be of reduced diameter and thus spaced with respect to the sleeve interior surface. The upper end of plunger 37 terminates within sleeve 30 and is engaged by a spring 40 positioned between the plunger and a shoulder formed at the upper end of the sleeve 30. The spring 40 biases the plunger 37 in a down position, see FIG. I wherein the open upper end of sleeve 30 is in registration with port 32. As aforenoted, the open upper end of sleeve 30 is in direct communication with the hollow interior of the handle portion 12. The plunger lower end 37a is preferably rounded, projects downwardly from sleeve 30, and is in continuous contact with a trigger lever 41 which is pivotally mounted at 42 to the housing 11. When the trigger is manually actuated in a clockwise direction to a position, as shown in FIG. 2, the biasing effect of spring 40 is overcome and the plunger 37 is moved upwardly breeding the communication which previously existed th'rough sleeve 30 between the port 32 and pneumatic fluid accumulated in the hollow handle portion. The effect of this break in communication with the port and pneumatic fluid will be discussed more fully hereinafter.

As seen in FIGS. I-3, the interior of the handle portion 12 terminates at its inner end in an annular cavity 43 which is formed in housing 11 and encompasses the upper end of cylinder 13. Thus, when the handle portion 12 is connected to a source of pneumatic fluid, cavity 43 will be continuously charged with pneumatic fluid.

Also fonned in housing 11 is a second annular cavity 44 which encompasses the lower portion of cylinder 13, see FIGS. l-3. Cavities 43 and 44 are separated from one another by a partition 45. The lower end of cavity 44 communicates with the interior of cylinder 13 through a plurality of openings formed in the cylinder wall. The upper end of cavity 44, on the other hand, communicates with the lower end 46a of a vertically disposed passageway 46. The upper end 46b of the passageway 46 communicates with cavity 15, when poppet valve 14 is in its fully up or open position, see FIG. 2. The communication of passageway end 46b and cavity 15 is dependent upon the relative position of poppet valve 14. When valve 14 is in its down position, see FIGS. 1 and 3, passageway end 46b is closed off by the annular periphery of valve 14.

The head member 24 in the form, shown in FIGS. 1-3, 5, and 6, is provided with a peripheral groove 47 wherein the closed inner end 47a thereof is offset downwardly relative to the open end 4712. Disposed within the groove 47 is a conventional O ring type seal 48 which is of such a size relative to the depth of the groove that it is adapted to shift within the groove depending upon the direction of movement of the head member 24. The diameter of seal 48 is such that it will normally assume a sealing engagement with the cylinder interior surface, see FIG. 6. The diameter of the head member 24 is slightly less than the interior diameter of cylinder 13. By reason of this latter diametric differential an annual narrow gap or space 50 is fonned which is adapted to interconnect the upper and lower portions I and II of the cylinder interior when the seal 48 is retracted within the groove, as seen in FIG. 5. The retraction of the seal within groove 47 occurs while the drive piston 23 is moving through its drive stroke due to the pneumatic fluid pressure exerted upon the upper face of the head member 24. The annular gap 50 permits a small portion of the pneumatic fluid driving the piston to bleed around the periphery of the head member. Such fluid bleeding during the driving stroke has a twofold purpose: (a) it expedites pressure buildup within cylinder portion II and effects more rapid return of the drive piston to its firing position, and b) it reduces friction between the drive piston head member and the cylinder wall during movement of the piston through its driving stroke.

Upon movement of the piston through its return stroke, as seen in FIG. 3, the pneumatic pressure accumulated in cylinder inten'or portion II initially flows through gap 50 causing a suction action to occur whereupon the seal 48 moves out of its retracted position and returns to its normal sealing engagement with the cylinder wall, as seen in FIG. 6. The seal 48 continues its sealing engagement for the balance of the return stroke due to the exertion thereon of the pressure of the pneumatic fluid accumulated in the cylinder interior portion Il. Thus, the interruption of the sealing engagement by the seal 48 has an additional benefit in that it prolongs seal life.

FIGS. 7 and 8 disclose a modified form of head member 24 having a peripheral groove 47' formed therein for accommodating a flat, ring-shaped flexible seal 48'. The inner portion 48a of the seal is snugly disposed within the groove 47 whereas the outer peripheral portion 48'b projects beyond the perimeter of the head member 24' and sealingly engages the cylinder wall 13 and closes gap 50 while the drive piston is returning to its firing position. It will be noted in FIGS. 7 and 8 that the peripheral portion of member 24' disposed beneath the seal 48' is undercut; thus. permitting room in which the outer portion 48b of the seal can flex downwardly while the head member 24 is moving through its driving stroke. Flexing of seal 48'!) as shown in FIG. 7 and retracting of the seal 48, as shown in FIG. 5, produces comparable results with respect to bleeding of a small portion of the pneumatic fluid from cylinder portion I to cylinder portion II during movement of the drive piston through its driving stroke.

The peripheral portion of head member 24' disposed above the seal 48 serves as an abutment against which the seal engages, see FIG. 8, while the head member 24' is in its return stroke.

FIG. 9 discloses a third form of head member 24" which includes a peripheral groove 47" disposed in encircling relation. Carried within the groove 47" is a double lip seal 48". Seal 48" has an inverted substantially U-shaped cross-sectional configuration with the outer leg L thereof adapted to sealingly engage the cylinder wall 13 during upward or return movement, see arrow in FIG. 9 of the drive piston head member. During movement of the head member in the opposite direction, the pneumatic driving pressure will cause the seal leg L to move away from the cylinder wall thereby permitting a portion of the compressed air to bleed past the periphery of the head member.

Affixed to the underside of housing 11 is the fastener-feed mechanism 35. The mechanism 35 is adapted to automatically and intermittently feed individual fasteners F into an elongated firing station 51. When the fastener F is disposed at station 51, the axis of the fastener is in substantial alignment with the axis of the piston driver blade 25, see FIG. 1. The illustrated fasteners F are round, fiat-headed nails which are arranged in spaced parallel relation and are interconnected by one or more flexible frangible strips or tapes T. The mechanism 35, as seen in FIGS. 1-4, includes a guide 52, which extends laterally from the firing station 51. The guide 52, as seen in FIG. 4, includes an air cylinder section 53 having a flat exposes wall 53a forming one side of an elongated narrow passageway P through which each fastener F of the collated fasteners must pass before a fastener F reaches the firing station 51.

The opposite side of the passageway P is defined by a plate section 54 which is hingedly mounted at 55 so as to pennit opening thereof thereby facilitating initial threading of the collated fasteners in the feed mechanism. Disposed at the outer end of the passageway P and removably secured to the mechanism is a fastener magazine or canister, not shown.

The air cylinder 53 is provided with a central bore 56 having one end 56a thereof enlarged and the opposite end 56b thereof of reduced diametric size. End 56a is sealed off by suitable closure means 57. Mounted for reciprocatory movement within the bore 56 is a pneumatically actuated feeder piston 58. The piston 58 includes an enlarged head 580 having a suitable peripheral seal 60 which is in sliding engagement with the wall defining the enlarged end 56a of the bore. The piston 58 also includes a stem portion 581) also having a peripheral seal 61 which is in sealing engagement with the wall defining the small end 56b of the bore. Pivotally connected at 62 to the distal end of the stem portion 58b is a spring biased pawl 63. The pawl has a serrated side 630 which projects through a suitable opening formed in the side of passageway P and is adapted to engage predetermined fasteners F during reciprocatory movement of the piston 58. The serrations formed in the side of the pawl 63 each have a tapered trailing side and a perpendicular front side. The tapered trailing sides permit the spring biased pawl 63 to readily cam over the fasteners F disposed in second and third positions from the end of the collated fasteners or from the firing station 51 as the feed piston is retracted. A conventional spring detent, not shown, is carried by plate section 54 which will prevent retrograde movement of the collated fasteners as the feed piston is retracted.

As aforementioned, the feeder piston 58 is pneumatically actuated by the controlled introduction of pneumatic fluid on one side or theother of the enlarged head 58a of the feeder piston 58. The introduction of the pneumatic fluid is accomplished through port 34, previously described, and an elongated port 64 formed in the housing 111. Port 64, as seen in FIG. 1, is disposed between port 34 and the annular cavity 44. The upper end of port 64, as noted, is in constant communication with the interior of handle portion 12 which is charged with pneumatic fluid. The lower end of port 64 terminates at the small end 5611 of the cylinder 56. The lower end of port 34, on the other hand, terminates at the large end 56a of the cylinder 56.

When the drive piston 23 is in its firing or static position, as shown in FIG. 1, and the trigger lever 41 is in its undepressed state, the feeder piston 58 has equal pneumatic pressure exerted on opposite sides of the head member 58a; however, because of a surface area differential, the piston 58 will assume its fully extended position whereby the pawl 63 has moved a fastener F into the firing station 51. Once the trigger lever 41 is depressed, the pneumatic fluid accumulated in the enlarged end 56a of the cylinder 56 and between closure means 57 and the outer surface of the head member 58 is exhausted to the atmosphere through port 34, port 32, and around the plunger 37 forming a part of the trigger valve 28. As the depressurizing occurs through port 34, the pneumatic fluid accumulated on the opposite side of head member 580 immediately causes the feed piston 58 to be retracted causing the pawl 63 to move away from the firing station 51 whereby it is out of the way of the driver blade 25 as it moves through its driving stroke, Because the trigger valve 28 controls the actuation of both the drive piston 23 and the feeder piston 58, a failsafe system is provided which assures that the feeder piston 58 will not interfere with the drive piston during its drive stroke.

As aforementioned, upon the piston 58 being retracted, the pawl serrations slide over the fasteners into the positions shown in F IG. 4 where they are ready to feed the next fastener F into the firing station 5] as the driver blade 25 is withdrawn therefrom. Thus, it will be observed that the feed piston 58 relies solely on pneumatic fluid for actuation avoiding the need for a spring to move the piston one way or the other. Past experience in prior art apparatus of this type has indicated that serious maintenance problems have been encountered when spring returns for pistons have been utilized.

Thus, it will be seen that a fastener-driving tool has been provided which is of simple construction, eliminates serious maintenance problems, prolongs the life of the seal carried by the driver piston head, expedites pressure buildup to effect quick return of the drive piston, and incorporates a fail-safe system with respect to the location of the feed piston during movement of the drive piston through its driving stroke.

We claim:

1. A pneumatically actuated fastener-driving apparatus comprising a housing having a reservoir adapted to be charged with pneumatic fluid; a cylinder disposed within said housing and having a first end thereof exposed at predetermined inter vals to said pneumatic fluid reservoir; a drive piston mounted within said cylinder for reciprocatory movement between said cylinder first end and a second end of said cylinder, said piston including an enlarged annular head member, an elongated driver blade extending from a first surface of said head member and axially of said cylinder and having a portion thereof projecting from the cylinder second end, an adjustable seal carried by and delimiting the periphery of said head member, and nonnally being disposed in sealing engagement with the cylinder interior surface, said seal being out of normal sealing engagement with the cylinder interior surface during movement of the piston from said cylinder first end to said cylinder second end and being in normal sealing engagement with the cylinder interior surface during movement of the piston from said cylinder second end to said first end; a pneumatically responsive first valve member mounted within said housing for movement between open and closed positions with respect to said cylinder first end, said valve member, when in said open position, exposing a second surface of said piston head member to said pneumatic fluid reservoir causing movement of said piston from said cylinder first end to said cylinder second end; and a manually actuated second valve member mounted on said housing for regulating the pressure differential applied to opposite surfaces of said first valve member to effect movement of the latter between said open and closed positions with respect to said cylinder first end.

2. The apparatus of claim 1 including a resilient bumper piece disposed adjacent said cylinder second end and engaged by the piston first surface when said piston is at a position adjacent said cylinder second end; said piston driver blade extending through said bumper piece and being movable relative thereto.

3. The apparatus of claim 1 wherein said housing includes a cavity encompassing a portion of the cylinder adjacent the second end thereof, a first passageway communicating at one end with said cavity and at the other end with the pneumatic fluid source only when said first valve member is disposed in said open position; said cylinder being provided with a port adjacent said cylinder second end and interconnecting said cavity and the interior of said cylinder adjacent said second end whereby pneumatic fluid accumulated in said cavity will be exerted against the first surface of said piston head member when the latter is disposed at said cylinder second end and effect return of said head member to said cylinder first end.

4. The apparatus of claim 3 wherein said housing includes a second passageway having one end thereof communicating with the interior of said cylinder adjacent said first end except when said first valve member is in said open position and having a second end thereof communicating with the exterior of said housing.

5. The apparatus of claim 4 wherein said housing includes a third passageway having one end thereof communicating with the pneumatic fluid reservoir only when said second valve member is in a nonactuated position, and having a second end thereof in communication with the surface of said first valve member opposite the surface thereof adjacent said cylinder first end.

6. The apparatus of claim 1 including a fastener feed unit mounted on said housing for feeding a fastener into axial alignment with said drive blade when said piston is disposed adjacent said cylinder first end; said feed unit including a second cylinder having the axis thereof angularly disposed relative to the direction of movement of said angularly blade, a pneumatically actuated piston mounted for reciprocatory movement within said second cylinder; a feed pawl adjustably mounted on said second piston and projecting outwardly from said second cylinder for successively positioning a fastener into driver blade alignment upon movement of said second piston in a first direction relative to said second cylinder; and a pair of passageways for pneumatic fluid having corresponding first ends communicating with opposite ends of said second cylinder whereby is exerted on opposite sides of a head member carried by said second piston to effect movement thereof, said pneumatic force differential being controlled by said second valve member; said second valve member, when manually actuated, causing a pneumatic force differential to be exerted on said second piston head member to effect movement of said second piston in a second direction whereby said feed pawl is moved to a retracted position relative to the path of movement of said driver blade.

7. The apparatus of claim 6 wherein said feed pawl is spring biased into engagement with a fastener during movement of said second piston in said first direction.

8. The apparatus of claim 7 wherein said second piston includes a second head member spaced longitudinally of said first mentioned head member and adjacent said feed pawl, the surface area of said second head member exposed to the pneumatic pressure being less than the exposed surface area of the first mentioned head member.

9. The apparatus of claim 1 wherein said piston head member is provided with an annular peripheral groove having a closed inner side offset relative to an open side in a direction toward the first surface of said head member, and said seal comprises an "0 ring adjustably disposed within said groove; said 0" ring, during movement of the piston head member from said cylinder first end to said second end, assuming a retracted position with respect to said groove, and during return movement of the piston head member to said cylinder first end, assuming a projected position with respect to said groove open side.

10. The apparatus of claim 1 wherein said piston head member is provided with an annular peripheral groove, and said seal comprises an annular flat resilient ring, said ring havmg the outer penpheral edge thereof projecting from said groove and when in nonnal position being in sealing engagement with the interior of said cylinder; the peripheral portion of said head member disposed between said ring and said head member first surface being undercut to provide a spacing for the ring outer peripheral edge to be flexed thereinto and out of engagement with the cylinder interior when said drive piston is moving from said cylinder first end to said cylinder second end.

11. The apparatus of claim 1 wherein said piston head member is provided with an annular peripheral groove, and said seal comprises a double lip member having an inverted substantially U-shaped cross-sectional configuration, one of the lips forming said seal member being disposed outwardly of the other lip and in sealing engagement with the interior of said cylinder only when said piston is moving from said cylinder second end to said cylinder first end.

a: n a w a:

CERTEFICATE 9F Patent No. 3 622 062 It is certified that error appears and that said Letters Patent are hereby Column 3 line 41 Column 3, line 64 i 1 Column 4 line 27 i i Column 7, line 25 5 (claim 5) a z 1 Column 7,, line 34 (claim 6) a 9 i Column 7 line 43 5 (claim 6) L v ,1" 5 Slgnec and sealer: 'Gfll-B .2 k

ORM PO-105O H0459] UNITED STATES PATENT GFFiCE CORRECTEGN Date November 23 1971 lnvent fl James K- Geode Jr and James A. Whiteside in the above-identified patent correcteci as shown below:

"annual" should be "nonactuated" should be --nonactuated delete angularly ancz substitute therefor -drive;:-

after rhereby" insert --a pneumatic force differential-- "I'd day of 'May 19??! ROBERT G-O dam Commissioner" of Patents USCOMM-DC 6O375-P59 US, GOVERNMENT PRINTiNG OFFICE 1959 0-305-334 

1. A pneumatically actuated fastener-driving apparatus comprising a housing having a reservoir adapted to be charged with pneumatic fluid; a cylinder disposed within said housing and having a first end thereof exposed at predetermined intervals to said pneumatic fluid reservoir; a drive piston mounted within said cylinder for reciprocatory movement between said cylinder first end and a second end of said cylinder, said piston including an enlarged annular head member, an elongated driver blade extending from a first surface of said head member and axially of said cylinder and having a portion thereof projecting from the cylinder second end, an adjustable seal carried by and delimiting the periphery of said head member, and normally being disposed in sealing engagement with the cylinder interior surface, said seal being out of normal sealing engagement with the cylinder interior surface during movement of the piston from said cylinder first end to said cylinder second end and being in normal sealing engagement with the cylinder interior surface during movement of the piston from said cylinder second end to said first end; a pneumatically responsive first valve member mounted within said housing for movement between open and closed positions with respect to said cylinder first end, said valve member, when in said open position, exposing a second surface of said piston head member to said pneumatic fluid reservoir causing movement of said piston from said cylinder first end to said cylinder second end; and a manually actuated second valve member mounted on said housing for regulating the pressure differential applied to opposite surfaces of said first valve member to effect movement of the latter between said open and closed positions with respect to said cylinder first end.
 2. The apparatus of claim 1 including a resilient bumper piece disposed adjacent said cylinder second end and engaged by the piston first surface when said piston is at a position adjacent said cylinder second end; said piston driver blade extending through said bumper piece and being movable relative thereto.
 3. The apparatus of claim 1 wherein said housing includes a cavity encompassing a portion of the cylinder adjacent the second end thereof, a first passageway communicating at one end with said cavity and at the other end with the pneumatic fluid source only when said first valve member is disposed in said open position; said cylinder being provided with a port adjacent said cylinder second end and interconnecting said cavity and the interior of said cylinder adjacent said second end whereby pneumatic fluid accumulated in said cavity will be exerted against the first surface of said piston head member when the latter is disposed at said cylinder second end and effect return of said head member to said cylinder first end.
 4. The apparatus of claim 3 wherein said housing includes a second passageway having one end thereof communicating with the interior of said cylinder adjacent said first end except when said first valve member is in said open position and having a second end thereof communicating with the exterior of said housing.
 5. The apparatus of claim 4 wherein said housing includes a thIrd passageway having one end thereof communicating with the pneumatic fluid reservoir only when said second valve member is in a nonactuated position, and having a second end thereof in communication with the surface of said first valve member opposite the surface thereof adjacent said cylinder first end.
 6. The apparatus of claim 1 including a fastener feed unit mounted on said housing for feeding a fastener into axial alignment with said drive blade when said piston is disposed adjacent said cylinder first end; said feed unit including a second cylinder having the axis thereof angularly disposed relative to the direction of movement of said angularly blade, a pneumatically actuated piston mounted for reciprocatory movement within said second cylinder; a feed pawl adjustably mounted on said second piston and projecting outwardly from said second cylinder for successively positioning a fastener into driver blade alignment upon movement of said second piston in a first direction relative to said second cylinder; and a pair of passageways for pneumatic fluid having corresponding first ends communicating with opposite ends of said second cylinder whereby is exerted on opposite sides of a head member carried by said second piston to effect movement thereof, said pneumatic force differential being controlled by said second valve member; said second valve member, when manually actuated, causing a pneumatic force differential to be exerted on said second piston head member to effect movement of said second piston in a second direction whereby said feed pawl is moved to a retracted position relative to the path of movement of said driver blade.
 7. The apparatus of claim 6 wherein said feed pawl is spring biased into engagement with a fastener during movement of said second piston in said first direction.
 8. The apparatus of claim 7 wherein said second piston includes a second head member spaced longitudinally of said first mentioned head member and adjacent said feed pawl, the surface area of said second head member exposed to the pneumatic pressure being less than the exposed surface area of the first mentioned head member.
 9. The apparatus of claim 1 wherein said piston head member is provided with an annular peripheral groove having a closed inner side offset relative to an open side in a direction toward the first surface of said head member, and said seal comprises an ''''O'''' ring adjustably disposed within said groove; said ''''O'''' ring, during movement of the piston head member from said cylinder first end to said second end, assuming a retracted position with respect to said groove, and during return movement of the piston head member to said cylinder first end, assuming a projected position with respect to said groove open side.
 10. The apparatus of claim 1 wherein said piston head member is provided with an annular peripheral groove, and said seal comprises an annular flat resilient ring, said ring having the outer peripheral edge thereof projecting from said groove and when in normal position being in sealing engagement with the interior of said cylinder; the peripheral portion of said head member disposed between said ring and said head member first surface being undercut to provide a spacing for the ring outer peripheral edge to be flexed thereinto and out of engagement with the cylinder interior when said drive piston is moving from said cylinder first end to said cylinder second end.
 11. The apparatus of claim 1 wherein said piston head member is provided with an annular peripheral groove, and said seal comprises a double lip member having an inverted substantially U-shaped cross-sectional configuration, one of the lips forming said seal member being disposed outwardly of the other lip and in sealing engagement with the interior of said cylinder only when said piston is moving from said cylinder second end to said cylinder first end. 